<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
        img {
            width: 300px;
        }
    </style>
  </head>
  <body>
    <img src="./images/s.gif" alt="" />
    <div>上午好</div>

    <script>
      var img = document.querySelector('img')
      var div = document.querySelector('div')
      var date = new Date()
      var h = date.getHours()
      if (h < 12) {
        img.src = './images/s.gif'
        div.innerHTML = '上午好'
      } else if (h < 18) {
        img.src = './images/x.gif'
        div.innerHTML = '下午好'
      } else {
        img.src = './images/w.gif'
        div.innerHTML = '晚上好'
      }
    </script>
  </body>
</html>
